1. Field of the Invention
The present invention relates to the communication apparatus, e.g., telephone terminal, fax terminal etc; that connects to a domain name system server (hereafter referred to as DNS server), the server having a ENUM (tElephone Number Mapping) function that stores and manages a telephone number and various destination information corresponding to the telephone number, and provides a user with the information according to a telephone number used for an inquiry by the user (hereafter referred to as inquiry telephone number).
2. Description of Related Art
In recent years of the rapid IP network service development, various researches have been done around the world, on an ENUM function that enables various applications for communication services (e.g., “IP telephones” including e-mail, telephone call, and Internet telephone call; and “IFAX” including fax and Internet fax) utilizing only a currently used telephone number.
A DNS server having the ENUM function is provided with a table that stores and manages a telephone number and destination information including communication service related to the telephone number (e.g. URI (Uniform Resource Identifier) such as e-mail address, ordinary telephone number, IP telephone number, fax number and IFAX number). For example, upon receiving notifications of an inquiry telephone number from a terminal apparatus, destination information corresponding to the inquiry telephone number is obtained from the table so that, out of all obtained destination information, the destination information only related to the apparatus type (service function), which is used by the inquiring terminal apparatus, is provided to the terminal apparatus (cf., non-patent article 1).
In a management table within a DNS server, a telephone number and various destination information corresponding to the telephone number (URI information) is usually registered by an operation setting of the user, under a permission of a person having the telephone number.
For example, when sending an e-mail from a terminal apparatus to a communication destination, the user of the terminal apparatus inputs the destination telephone number in an e-mail destination field of the e-mail application, while maintaining the e-mail application of the terminal apparatus, and executes a transmission command of the e-mail.
The DNS server, upon receiving the telephone number and the transmission command from the terminal apparatus, searches the management table for an e-mail address corresponding to the telephone number and returns the obtained e-mail address of the destination to the terminal apparatus.
Upon receiving the e-mail address of the destination from the DNS server, the user of the terminal apparatus can e-mail the destination using the e-mail address.
According to the DNS server having the above described ENUM function, the user of the terminal apparatus can easily obtain the destination information as long as the user has the destination telephone number, even if the user does not have the complete destination information (such as e-mail address or IFAX number of the destination). [Non-patent article 1] Shigeki GOTO et al., “Internet telephone and ENUM” [on-line], Oct. 18, 2002, Japan Network Information Center, [searched on Nov. 25, 2003], Internet <URL: HYPERLINK http://www.nic.ad.jp/ja/materials/after/20021018/ENUM20021018.PDF>
When the terminal apparatus, connected to the DNS server having the described ENUM function, transmits a destination telephone number to the DNS server, in ordered to obtain the destination information, the destination information can be obtained from the DNS server. However, when the terminal apparatus using a telephone service function transmits an inquiry telephone number to the DNS server, for example, only the destination information related to the ordinary telephone service is obtained from the DNS server, even if the destination information related to an IP telephone is also managed in the table. In other words, the user of the terminal apparatus is only notified of the ordinary telephone information and is not notified of the available IP telephone information, which has a cheaper communication cost. Therefore, the conventional technology provides no option for the user to choose the IP telephone, which has the cheaper communication cost. This problem can be seen not only when using the telephone service functions, but also when using other service functions that employ IP communication, such as an IFAX service function with respect to the ordinary fax service function.